A court heard that, just an hour before, the 36-year-old had also been loud and abusive in a pub before smashing up the windscreen of the landlord’s car.

Curran was arrested and pleaded guilty to one count of exposure, on public order offence and criminal damage at North Tyneside Magistrates’ Court, where he claimed he couldn’t remember anything because he was “paralytic”.

Rebecca Gibson, prosecuting, told the court the indecent exposure happened at 5.30pm on April 28.

She said: “The witness was driving through Station Road, which is a busy main road.

“She noticed a man and thought he looked like he was stretching against a car bonnet, as if he was about to go for a run.

“She looked again and noticed the car was a black BMW, which was parked up. The male was in front of the bonnet.”

In a statement from the witness, she said: “I then saw the male had his genitals hanging out the front of his shorts...he was gyrating and thrusting against the car bonnet. I thought, ‘The dirty b******, he’s having sex with the car’.

“I couldn’t believe a man would stand in public, fully thrusting against the bonnet of a vehicle.” The court heard the witness drove on and saw an unsuspecting mother and young child walking towards Curran.

After returning home to get her mum and brother, she went back to Station Road but found the car gone and Curran, previously of Osborne Road, Jesmond, Newcastle, but now living at Holmlands, Whitley Bay, sitting fully clothed on a nearby wall.

Curran was arrested and it was soon revealed that, just an hour earlier, he had entered the Black Horse Inn, in Monkseaton, North Tyneside, and become loud and aggressive before throwing a charity box at the bar.

Mrs Gibson said: “He then picked-up a bar stool and went outside.

“The landlord, James Read, heard a large smash and saw the defendant by his car, a Citroen Berlingo, where he threw the bar stool to the ground and walked away.

“Mr Read saw the windscreen of his vehicle had been smashed. The damage cost £216.”

Mark Harrison, defending, said Curran was deeply remorseful for what he’d done. He said: “The police didn’t consider this sinister behaviour. They described it more as drunk stupidity. I don’t ever recall a more embarrassed, ashamed and remorseful individual. He hasn’t stopped apologising.

“There had been a fractious breakdown of the friendship between Mr Curran and the publican. He accepted there had been a disagreement and, in the spur of the moment, doing damage to the car.

“What happened later, was frankly unbelievable. He can’t put an explanation to it because he can’t remember it.”

The court also heard Curran suffered from post-traumatic stress disorder from his time in the marines.

Magistrates’ adjourned sentencing for the preparation of reports.

Curran, a love rival of Andy Carroll, was once arrested but never charged over an arson attack on the footballer’s car in 2010,

The former security specialist, who used to command a six-figure salary protecting the wealthy and influential oversees, also spent five months behind bars in 2012 for crashing his car head-on into a taxi and brandishing knives in a village pub.